An uninterruptible power supply (UPS) refers to a system that provides backup power to a load during loss of an input power source. Often times, the backup power is provided by a battery. UPS systems are used in various applications where continuous power is needed. For example, a UPS system can be implemented to protect electrical systems from corruption and/or loss of data. During normal operation of common UPS systems, a primary power source supplies power to the load and also charges the battery. During loss, malfunction or non-operation of the primary power source, the backup battery supplies power to the load. As a result, an uninterruptible supply of power can be continuously provided to the load. Conventional UPS systems do not provide for intelligent control of backup battery power. It would be desirable to have a simplified circuit and/or intelligent control that improves efficiency and reliability of backup power in UPS systems.